Permian dietary fiber

On Nova Science Now on PBS last night they reported about work studying the contents of small liquid inclusions in New Mexico’s Saledo salt beds that were  laid down in the Permian era 250 million years ago.

The report showed fascinating electron micrographs of mats of cellulose in the inclusions – hi-fiber salt  no less!

The cellulose was identified by it resistance to hydrolysis in 0.5 N NaOH and it susceptibility to hydrolysis by beta 1-4 specific cellulase enzymes.

So cellulose is not only the most abundant organic molecule on the earth, it is now the oldest identified macromolecule. Not bad for a bunch of glucose.

Secrets in the Salt…

can be seen  in its entirety at this link.

The researchers, Jack D. Griffith, Smaranda Willcox, Dennis W. Powers, Roger Nelson, & Bonnie K. Baxter published the work in Astrobiology in April 2008 (Griffith et al 2008 Astrobiology 8 (2): 215-228. doi:10.1089/ast.2007.0196.  Discovery of Abundant Cellulose Microfibers Encased in 250 Ma Permian Halite: A Macromolecular Target in the
Search for Life on Other Planets
)..

No image – because the copyright holders want to charge a USD$86.50 fee for use of ONE image from the paper just in A SINGLE  email, let alone what they’d charge for a blog, notwithstanding the free advertising they’re getting.

You need to go to the PBS site for the electron micrographs.

Food relationship not immediately evident…

Calculus…

From “Built on FactsSunday Function #40. It might make some of those pesky integrals a bit more real for you. These concepts are very important in food engineering, which affects, and is affected by, the chemistry.

Squirrely physics

Image attribution: Matt Springer – Built on Facts

Also from “Built on Facts” from a little while ago, highlighting that “ratios of volume to surface area are hugely important in biological processes” and these include elements related to food processing, like particle size distributions, and hydration rates, and heat transfer.

It is worth reading the article.

Open you fermentation horizons & mobile microscopy

A new post “Forays in Fermentation” from Jeremy at the Agricultural Biodiversity Weblog, via Research Blogging highlights two recent papers on fermentation that go beyond the usual beer/wine paradigm that I see in some students that choose our fermentation option.

The papers are

  1. Nout, M. (2009). Rich nutrition from the poorest – cereal fermentations in Africa and Asia Food Microbiology DOI: 10.1016/j.fm.2009.07.002 []
  2. Poutanen, K., Flander, L., & Katina, K. (2009). Sourdough and cereal fermentation in a nutritional perspective Food Microbiology DOI: 10.1016/j.fm.2009.07.011

We have used idli (rice & mung beans & a small amount of fenugreek) and injera (teff -  Eragrostis teff) as demonstration fermentations in the Topics in Fermentation – Science of Baking class. They are quite interesting. The idli ferment smells for all the world like yoghurt, apparently from a colonization of lactic producing bacteria. We kicked off our injera by chewing some of the grain and returning it to the mix, giving an inocculum of acid forming bacteria [better not done immediately after cleaning your teeth] and amylase from saliva to provide the two essentials – fermentable sugars and fermentation organisms.

The paper by Nout looks like a good read.

Microscopy comes to Web 2.0

I have been looking for ways to streamline our experience of viewing the diversity and behavior of starch granules outside the traditional transmission microscope exercise we have done in Food Chem labs – most students, and I, who don’t use microscopes everyday, often have trouble setting them up, and as an instructor, with multiple microscopes in a lab, I don’t know if students are seeing what te ought to be.

A new development in clinical microscopy…

Breslauer, D., Maamari, R., Switz, N., Lam, W., & Fletcher, D. (2009) Mobile Phone Based Clinical Microscopy for Global Health Applications. PLoS ONE, 4(7). DOI: 10.1371/journal.pone.0006320

for adaptation to a mobile phone (or I guess, my FlipCam) would let us all see a share our visions of starch granules, and share in real time the excitement [well, I am a food chemist] of seeing starch granules literally explode when we douse them with 1 normal hydroxide.

For more see Dan Gorelick’s post at Science Planet , which I also found via my RSS feed from Research Blogging.

Science outreach summer

So far this summer I have given two short workshops using wheat, flour, bread,  and baking as a way of bringing food chemistry to life.

The First group was the

Oregon Farm Bureau’s  Summer Agriculture Institute

on the theme of Grain-Gluten-and Great bread. And started with the quote from Henri Fabre a 19th C French entomologist.

“History celebrates the battlefields whereon we meet our death,
but scorns to speak of the plowed fields whereby we thrive;
it knows the names of kings’ bastards
but cannot tell us the origin of wheat”
.

We worked through H.E. Jacob’s “Rivalry of the grasses” from “6000 Years of Bread” on the theme that wheat was ascendant partly because it made risen products with palatable textures as a result of the unique properties of gluten proteins [their stubborn insolubility, the ability of the large glutenin molecules to cross-link into enormous (by molecular standards) elastic networks, and the viscous contribution of the gliadins leading to the viscoelasticity of wheat flour dough].

We looked at the fracture properties of grain during milling and how these are related to a single gene that determines if wheat kernels are soft or hard. Then through the genetics of gluten diversity and finally to experiencing some of this in breads and doughs. it was a lot of fun, and we had great bread to eat as well.

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The Second Event was the…

Apprenticeships in Science & Engineering (ASE) Mid-Summer Conference

workshop for high school juniors and seniors.

This year we went with the TSoB (the science of baking) workshop again. But this time enhanced with hands-on dough mixing, and sprinkles of…

Polymer chemistry – dough and gluten properties
Physical chemistry – dough hydration and mixing
Physics/Rheology – fracture mechanics in milling, dough properties, bread texture
Organic chemistry – Maillard browning reactions
Physics – the gas laws & rising bread
Biochemistry – fermentation
& Genetics

All the students were remarkably engaged with the topic, helped along by a bribe of very fresh baguettes. The teachable moments were abundant but it seemed the most effective were;

-to experience the relationship between weak and strong dough and dough elasticity by rolling out dough  by hand.

-to hand mix a dough from scratch and to experience the rate of hydration and to feel gluten devlopment and to get to understand why we need air in dough (an aqueous phase saturated in CO2 cannot spontaneously create gas bubbles, they need to be prenucleated in the dough).

-to experience the relationship between water activity and crust browning.

We had a lot of fun and are looking forward to next year.

I don’t have clearance yet to show faces, but even the hands tell a great story about student engagement !

We have one more workshop planned this summer for the K-12 science and math teachers of Lincoln County Oregon.

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More silly putty science via Mike the Mad Biologist at ScienceBlogs

We use silly putty in class, both the Food Systems Chem and my graduate Food Polymer Science classes,  to get a handle [literally] on aspects of non-linear visco-elasticity of materials. Mike the Mad Biologist at ScienceBlogs linked to this video story at 30threads.

It pays to know your raw materials

Don’t mix up your mung beans and poppy seeds.  From Science Punk

Wine Authorities: Rosé from the Friday Fermentable

Terra Silligata

Why does my pita puff ?

Pita is made from one layer of dough, not as some think 2 layers that are joined at the edges.

So how does if puff?

The dough is often given a final proof that is drier than for risen breads. When the bread hits the hot oven the slightly dry skin seals. Really thin flat breads like pita can be baked at extreme temperatures. My lab in Sydney when I worked there used a pottery kiln for our routine test-baking of pita, and we baked them for 30 seconds at 550 degrees CELCIUS (about 1020 degrees F). Not unlike the conditions in a tandoori oven.

The sealed skin first constrains the existing gases in the small amount of dough that will turn to crumb. These expand and exert more pressure in line with the gas laws. There MAY be a VERY brief moment of additional carbon dioxide production from yeast but this will be really limited in the thinner types. But the greatest gas production and pressure comes from the water in the dough that turns to steam, lots of gas an pressure now. If you see the video in my last post you’ll see the outcome. The interior splits at the weakest point creating the taste sensation of fresh, high temperature baked pita bread. Good enough to eat on its own.

You can access a schematic of this on the google books preview of Jalal Qarooni’s Flatbread Technology book (page 71).

And why does my poolish lose weight ?

I commonly bake using a yeast poolish, a mixture of equal weights of flour and water, and a vanishingly small amount of instant yeast that is allowed to ferment overnight or longer. This long pre-ferment creates bread of outstanding flavor.

Anyway, I am, as many bakers are, in the habit of scaling out the exact amount of poolish I will need for a dough (I always bake using formulations that list ingredients by weight).In the morning i use the poolish assuming the same weight. Duh !! Some chemist I am.

Out of error the other day I had more poolish than I needed. When I weighed what I had I had 952 g. The evening before we had scaled out 500 g flour, 500 g water, and 1.5 g yeast (1001.5 g). It is clear that we’d lost in the order of 5% of the poolish weight. As I had covered the poolish I assumed this was not water loss, but loss of carbon dioxide (and maybe volatilized ethanol). Poolishes rise but at 100% hydration they are pretty weak and sloppy and gas loss would be expected.

If this was the case the weight loss would come from the conversion of starch to maltose , and the conversion of the maltose, via the fermentation pathway to CO2 and ethanol with the subsequent loss of volatiles. Anyway the result is a poolish that is more than 100% hydration (1.11 %) as the substrate comes mostly from the dry solids part of the poolish (although maltose requires the addition of 1 water molecule when hydrolysed to 2 glucose). This probably isn’t enough difference to cause dough handling problems and I can just go back to my weigh out the poolish the night before assumptions and not worry about it (until I do any poolish research, with the aim of eating the experimental outcomes of course.)

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